Method of producing tone effects in wireless telegraphy.



M. BASTHAM.

IBTHGD OP PBODUCING TONE EFFECTS IN WIRELESS TELBGBAPHY. APPLIoATIox rILnn s291220, 1011.

150256,893. Patented Manz, 1913.

2 BEEETBf-BHBBT 1.

witnesefff Inventor? M. BASTHAM. METHOD 0E PEoDUING TONE EEEEoT's 1N WIRELESS TELEGEAPHY.

APPLIGATION FILED SEPT.20,1911. 1,056,893, l Patented Mar. 25, 1913 2 SHEETB-SHBBT 24 4 .A L JMW" da wd@ @62 f' f( au UNITED STATES PATENT. ernten- NMELVILL EASTHAM, or CAMBRIDGE, MASSACHUSETTS, As'sIGNoR To cLArP- 'EASTHAM com-ANY, or oAMBnIDGE, MASSAQHUSETTS, A coRronATIoN or mSsacHUsiaTTs.

` METHOD OE PRODUCING TONE EFFECTS IN `WIRELESS TELEGRAPI-IY.

To'oll 'wlwmz't may concern: 1 i

Be it known that I, MELvrLLn EAsTHAM, a citizen of the United States, and resident of Cambridge, in the county of Middlesex and State of Massachusetts, have in vented new and-useful Improvements, in Methods of Producing Tone Effects in llVireless l.l`elegralphy, of which the following is a' specification.;y A p My invention relates to wireless teleg- 'r'aphy, and consists of a method'of producwireless telegraphic apparatus.'

-Theobjects of my ..invent1on are as follows: To produce tone-effects, similar in muing'regulable tone-effectsl in the operation of sicalregularity to those obtainable by the use of'v high-frequency generators "and synchronized spark-interrupters, while employl'ing' generating apparatus of ordinary. commercial frequency and securing the economy,

- advantage and efficiency due to 'the use-.of

' foruaccurate tuning by effective damping of such generators. To eliminate` thefnecessity spark-oscillations Tov adjust the tone to any .pitch desired -within the practicable acoustic limits, particularly to regulate the .tone-pitch to suit the peculiarities and limitations of telephonie receivers. To employ low potentials (as contrasted with those which have prevailed in the operation of wireless .telegraphic circuits) by utilizing the. acoustic efficiency of comparatively faint regular musical tones, as contrasted with unmuslcal irregular crepitat-ions, and thus to facllltatethe insulation of condensers and antennae. To render the operation of `wirel less apparatus practically noiseless.

-My invention is characterized by the production of a train-discharge, and by breaking the normal continuity of the train into recurrent train-groups, separated by intervals of no discharge, and'determining the frequency of recurrence of these traingroups; then producing a tone effect in cor respondence to the train-group frequency, and' therefore independent of the generator frequency. The tone produced is the simple tone which corresponds to the frequency of recurrence. of the group of trains and Vis not.

sensibly-or perceptibly atleastfaflectedor modified bythe generator cycle undulations, or by any Superpositions of disturblng'overtones or crepitations ('by the trains themselves) Specification of Letters Patent. Patented Mfal. 25., 1913. Application led September 20, 1911. Serial No. 650,452.

- My invention' mayV advantageously be 55 practised with an apparatus such as illustrated in the drawings hereto annexed, in which,- D

Figure l diagrammaticelly represents parts `of a wireless telegraphic circuit and 6o shows a formof my novel spark gap device, in side elevation; Fig. 2 shows inl diagram details of Vthe spark gap devices; Fig. 3 shows in diagram certain" details of the said devices; Fig. 4 shows a .portion of a spark 65 gap disk; Fig. 5 illustrates diagrammati- Ically a single train-discharge; Fig. 6 illustrates dia-grammatically the separation of groups of train discharges, the groups occurring at acoustic .frequency, independent of generator-frequency, and Fig. 7 illus-f trates diagrammatically the ldivision of discharge into groups of trains, the groups occurring as units at acoustically,satisfactory frequency. u The inventions embodied' in thisapparatus, so illustrated, form the subject matter of an application for patent filed by me concurrently herewith, Serial Number 650,398.

Referring to Fig. l: G represents an'alter- 80 mating current generator set, which includes the-Step up transormer T. The cycle-frequency of the generator is preferably that of the usual commercial type and practice, say, 60. The circuit: which is excited by the transformer -'l` also, as usual, comprises the wires l and 2, capacity K, inductance T and a spark gap device, comprehensively designated by S. The frequency of the generator (l immaterial, except that for economy and convenience it .should be low. Indeed` the circuit which comprises the spark gap S may be excitcdby a constant-potential generator. The spark gap device S is herein represented hy two disks A and B; being mounted on the shaft C to rotate in the bearing D. driven by the pulley P from any suitable source of power; the disk A being inounted in the insulating plate E. Adjustment of the two disks A and B is provided for by securing the pulley P to the shaft C by means of a set Screw g, so that the face g `of the pulley may be adjusted to bear on the end of the housing D and secure any'desired spacing of the disk B from the disk A. The lO face g mayfbe heldagainst the housing by some simple means, as by leading the drivingbelt (not shown)f:`rom the pulley P at a slight. angle. The housing D is extended to form a box to inclose the disks A and B, the core E, of insulating material, being secured as shown. The plate A, mounted in the core plate E, may be provided with ex ternal fins or plates F, for heat-radiating purposes. The two disks provide the 'spark gap in the circuit. The opposed faces of the disks A and B are circular. Each is milled to form salientsectors a on the disk A, and b on the disk B (see Figs. 3 and 4). The sides of these sectors are not t-ruly radial, but are inclined to the radius by 'such an angle that wh'en'in the rotation of the-disk B a sector b is symmetrically opposite the interval between two sectors a on the disk A, that is to say, is just midway between l the two sectors a, the edges of the sector b `cuit as indicated in Fig. 1.

ential arc subtended by a sector 2L or b is less shall be parallel to the edges of the respectively adjacentsectors a, and distant therefrom by slightly more than the extreme sparking distance. The relation between the disks and their sectors is shown in diathan that subtended by an interva (a or lb) between two salient. sectors, pre eably about three fifths thereof. l By making the two members A and B alike, an ample extent of surface is provided and arc-formation effectively restrained. By adjusting the surfaces of the opposed salient sectors a. and b so that they are but slightly separated., a spark may be established between them at relatively low potentials.

The operation of the 4apparatus is as folf lows: Assuming that a 60 cycle generator is employed the rotary sector-disk B is rotatedat such speed that each salient sector b passes an opposite sector a with high frequency as contrasted withthe generator-frequency, say 600 times a second. The establishment and interruption of spark communication thus will produce, say, GOO isolated t-rain-groups per second. If the circuit is, for instance, adapted to charge the condenser about 18000 times per second the operation of the train interrupt-ing devices will produce 600 train groups per second,

` with l5 discharges per group on the average 'assuming the discharge to take place about' half the time. The number. of discharges will vary from group to gro'up, depending on the amount of power consumed in the circuitand on th'e stage in the generator cycle undulation at which a discharge occurs. The abundance of highly heat conductive ymaterial in the spark-members causes effective damping of oscillations, so that the excitation of the coupled circuit represented at T2 is by impact, and tuning is unnecessary.

The rate at which the train groups occur entire lenth of each sector-'edge,-as will produce spar fail.l

The train-groups produced by the above described apparatus according to my method will be established at that point discharge interruptions without where the potential attainsy sparking in'-4 tensity, and ,will .be discontinued when in the decline of the electromotive force the potential falls below the` sparking-intensity.

Theoretically therefore there will be interruptions in the regular continuity of lthe train group series, and electrically speaking this dlscontinuity must exist. Acous- -tically, however, no 'such discontinuity is perceptible. It might be supposed that the recurrence of maxima in synchrony with the generator cycle would pr duce an undertone, but so far asI have observed this does not occur..

The high heat-conductivity and relatively large mass of the sector disks and the metal,l

part of the housing will suffice, in apparatus of moderate capacity, to control temperatures. It is advantageous to have the housing of these disks closed, since constant circulation of fresh bodies of air tends to oxidize the metal-surfaces and thus deteriorate their efficiency. Complete closure of the housing also suppresses the noise of the sparking devices and quiets the operation of the apparatus. i

The method may still further be explained by reference to Figs. 5, 6 and 7, in which the irregular line t represents a singledischarge-train, which oscillates to a point of rest in an infinitesimal of time. These trains follow each other with greater or less rapidity according to the stage in the potential-cycle at which they occur, and, with a sparking apparatus as above described, the trains are produced only when segments of the spark-terminals are Within spark-dis` tance. of each other. Thus, in Fig. 6, P denotes the current curve in the sparking circuit during one half a enerator pbase. The abscissae laid upon the line of origin (A), repthe positions of the spark-terminal segcause spar charge trains number tive.

'the discharge trains, and

ment-s a, b, (Figs. 3 and 4) will permit discharges. are represented by the distances d', d, ds, etc., to d. At the stage represented by d, sup ose 'the potential too feeble to" discharge, while at thestage` the potential rise produces two discharge trains. The lines t, t each represent a discharge-train-such as is more completely illustrated in Fig. 5. At station clthe dis- Thel two discharge-trains which occurred during stage d constitute a. train-group; so also the tive discharge-trains during stage d. Each train-group-is designated as gt.

d the train group gt comprises nine trains t, at d* 'twelve or more, while at d, ai, dT and d, the fallin current produces fewer and `fewer trainischarges to each group, while'd, like d, is silent. f, as hereinabovev suggested, a source of constant potential be employed, the lfrequency of thel generator becomes zero; yet, with the provisionsfor producing regularly recurrent groups of4 train-discharges, the result` may be the same, acoustically considered, as with, say a 60 c cle alternating generator. Thus.l in Fig. 7 indicates constant potential, and

'-0 the line of originen which time-absciuae are laid oil. d,'d, d2 etc., represent the regularly determined sparking stages, t gt the groups of trains, which, other conditions being supd to'be the same, will each comprise the average vnumber of discharge trains t as represented by the cyclically increasing und decreasing groupdensities represented in Fig. 6. The silent stages which occur when alternating current generators are employe'd, do not sensibly affect the acoustic results.v

What I claim and desire to secure by Letters Patent is:

1. `The method of regulating the emission of electrical waves which consists in generati frequency discharges in groups of For stagetrains,recurring at regular frequency which is independent of the frequency of the generator employed.

2. The method of regulating theleinission of electrical Waves which consists in exciting a circuit with Vpotential at .relatively low frequency,'generating high frequency discharges divided into groups of trains in said circuit, said groups recurring sit-regular A intervals with frequency'intermediate between the ,exciting potential frequency and that ofthe discharge 'trains whichconstitute the groups. y

'3. The method of regulating the emission of electrical waves which consists in exciting a circuit with potential -alternations of relatively low frequency, generatingy high frequency discharges in groups of trains r e curring at regular intervals with frequencyinter-mediate between that of the potential alternations and that ofthe discharge .trains which constitute the groups'. I

4. The method of producing electrical waves suitable for the production of audible tone e'ects which consists in generating high frequency discharges divided into groups of trains recurringat regular and acousticallysatisfactory frequency findependent of the 'frequency of the 'generator employed.. i f

5. The method of producing electiical waves suitable for the production of audile tone effects which. consists in excitin a circuit with potential at relatively low equency, generating. 'high frequency discharges divided into groups 'of'rtrains in the circuit, sind groups recurring at regular.

and acoustically satisfactory intervals with frequency intermediate between the exciting potential frequency and that of the discharge trains which'constitute the groups.

Signed by me at Boston, Massachusetts` this .eighth day ofv September, 1911.

M .lllJV l'LlJE EASTHAM.

lYit-nesses z CHARLES D. lVoonnsRnr, Omsq lounn'is. 

